Effect of street conditions, including saline aerosol, on growth of the Small-leaved limes

There is increasing number of trees dying in large urban agglomerations. The problem is mostly pronounced in the case of street trees. In Polish cities, apart of pollutions generated by traffic, an important factor that causes death of trees is high salt concentration as a result of winter salt application for de-icing of streets. The aim of the study was to assess the growth of limes (Tilia cordata) planted along highly trafficked Warsaw street and exposed, among others, to salt in a form of saline aerosol. The assessment of shoot length, tree height and crown volume, based on the photographic method of the three increment assessments, showed very restrained growth of the studied limes. In the years 2006-2008 the trees performed so poorly as in similar period of 2003-2005 and grew worse than limes form natural habitats. In 2009 we even observed decrease in size of street trees as compared to 2008 which suggests both very bad condition of street habitats and the studied trees. Salt concentration measured on the surface of tree buds and shoots (EC) was higher in street trees than in trees from natural habitats, which indicates that saline aerosol is the source of sodium chloride. We observed highly diversified reactions of individual trees to the whole complex of street conditions. It is therefore recommended to select for propagation individuals from among most tolerant and vigorously growing plants (genotypes) to be used in street planting.